Electric winding



Feb. 17, 1948. DENTREMONT 2,436,207

ELECTRIC WINDING Filed Dec. 29, 1945 2 Sheets-Sheet l Inventor: Franklin RDEntPemont,

Feb. 17, 1948. DENTREMONT 2,436,207

ELECTRIC WINDING Filed Dec. 29, 1945 2 Sheets-Sheet 2 Inventor": Franklin RDEntremont,

b5 His Attorney.

Patented Feb. 1 1948 UNITED STATES PATENT OFFICE ELECTRIC WINDING Franklin R. D'Entremont, Lynn, Masa. assignor to General Electric Company, a corporation of New York Application December 29, 1945, Serial No. 638,058

18 Claims. (01. 175-358) 2 This invention relates to electrical induction The invention will be better understood from apparatus and more particularlytoimprovements the following description taken in connection in current transformers. with the accompanying drawing and its scope will In certain transformers of the above-menb pointed out in the appended claims. tioned type it is necessary to have a multi-turn In the drawing Fig. 1 is a partially broken away primary winding whose current carrying conducside elevation view of a transformer embodying tor is of large cross sectional area. Such transmy invention, Fig. 2 is a sectional view of the formers often have a two legged core and in transformer taken on line l-i of Fig. 1, Fig. 3

order to improve the characteristics of the transshow the double coils of the primary winding of former it is desirable 170 have its P y W n 1' the transformers shown in Figs. 1 and 2 before and its secondary winding each divided into two they are interconnected, Fig. 4 shows how the pricoils which are on the different legs of the core. mary winding of the transformers is formed by One way of winding a two coil primary winding interconnecting the coils shown in Fig. 3, Fig. 5 of heavy bar or strap conductor forms the .subshows a modified primary winding construction ie t matter of Patent 2,374,018. sranted Aprll 17, u having three turns, and Fig. 6 shows the double 1945, on an application of Harold E. Johnson and coils from which the primary winding of Fig. 5 is assigned to the present assignee. While the made. Johnson winding is very satisfactory for certain Referring now to the drawing and more parapplications, it requires that the heavy strap conticularly to Fig. l, the transformer is shown as ductor be very accurately precut as tolength and comprising a two legged core i of any suitable the winding must be made very carefully if the type, it being shown by way of example as being terminals are to be in proper alignment and have of the wound. type. Surrounding the two legs of the proper spacing. These latter factors are imthe core I are coils 2 and 3 which together conportant when the core and coil assembly of the stitute the secondary winding 01 the current transformer is tobe mounted in a preformed casa transformer. Surrounding the secondary coil 2 ing and also when the transformer is to be interis a primary winding coil 4 and surrounding the changeable with others. secondary winding 3 is a primary winding coil 5. In accordance with one of the features of a The primary winding coil 4 is provided with a preferred form of this invention the primary heavy terminal bar or strap 6 and similarly the winding of a current transformer consists of sea primary winding coil 5 is provided with a heavy rially connected duplicate separately and speterminal bar or strap 1. cially wound coils. These coils are character- As shown in both Figs. 1 and 2. the primary ized by having one end or terminal split into two winding coils are made of relatively wide and thin parts having normally parallel surfaces on oppostrap conductors which are embedded in suitable site sides of the coil so that the coils can readily u insulation I. be fitted together and aligned before their electri- Wrapped tightly around the outside of the two 'calinterconnectlons are made permanent. These primary coils 4 and 5 is a reinforcing band or permanent electrical connections are typically strap 9 which may be of steel. The purpose of made by brazing. this band is to prevent deformation of the pri- In a ord nce w h n h fea e f th in- 0 mary winding under conditions in which extra vention the two coils of the primary winding are large currents flow through the primary winding. surrounded by a tight reinforcing band so as to The ma netic effect of such currents is to tend to prevent distortion of the coils under short circuit make the coils assume a circular cross section, and conditions and so as mechanically to strengthen then to expand, and if they were allowed to do the transformer structure. This reinforcing 45 this their conductors would pull away from the band may be made of steel and as it surrounds insulation and thereby effectively destroy the the coils on the outside it does not link the core transformer. It will be observed that the band flux and does not constitute a short circuited l in'surrounding the entire core and coil strucc duc tu w th esp to the core fillxture does not link any of the transformer flux, This band also serves as a shield to reduce the and thus it does not inany way affect the elecflux ente in the core from a return conductor. trical characteristics of the transformer.

An object of the invention is to provide a new The primary winding, as will be seen from Fig. and improved electrical induction apparatus. 2, is a two-tum four-conductor winding. The de- Another object of the invention is to provide tails of this winding are shown'more clearly in a strong compact current transformer for heavy Figs. 8 and 4. Considering first the coil 4 shown current service. in Fig. 3, it will be seen that there are four radi- A further object of the invention is to provide ally superposed conducting bands or straps. All a new and improved multi-tum current transof these straps have one end aligned with an edge former primary winding of heavy current carryof the terminal 6, and they are electrically coning capacity. 00 nected to the terminal 6 in any suitable way such as by brazing. The four conductors then make substantially one complete turn together, this turn being generally rectangular in cross-section. At the point ID the outermost conductors, considered collectively as H, terminate while the two innermost conductors, which will be considered collectively as l2, continue for substantially another one-half turn to the point i3 which it will be observed is substantially diametrically opposite to the point I ll and thus is one-half turn away therefrom. At point l3 the innermost conductors l2 project tangentially away from the coil to form a straight terminal surface 14 which, although on the opposite side of the winding from the end ill of the outer straps II, is generally parallel with the outer surface of the straps l l. A strip of insulation I5 is inserted between adjacent strips which have a potential difference of 1 turn.

It is not essential to have four conductors as illustrated and it will be obvious to those skilled in the art that so far as my invention is concerned the double conductors II and I2 can be single straps or conductors if desired. Furthermore, as far as the principle of my invention is concerned, it is unnecessary to have the conductor stranded at all, and it can be solid up to the point l where the coil divides into the outer short part II and the inner long part l2. Thus the coil 4 is characterized by having three terminals 6, H and I4, the latter two being the respective ends of two effectively parallel parts of the coil which have a; common terminal 6.

The coil 5 is preferably a duplicate of the coil 4. Therefore, with the exception of its terminal 1, its parts which correspond to the parts of coil 4 are given corresponding primed reference numerals. Coil 5,'ho wever, has been rotated 180 degrees on its axis, relative to the position of coil 4 so that the terminals 6 and 1 of these coils extend away from each other as in Figs. 1 and 2. It will be observed that the tangentially extending projections l4 and H of the two coils are parallel to each other, and are also parallel with the surfaces M and I! so that these COils may he slipped together as shown in Fig. 4. However, it isnecessary to provide a piece of insulation 15 between the coils because their adjacent conductors are not at exactly the same potential and in fact are separated by the potential of one-half turn. In Fig. 4 the coils have been pushed together so that the part I4 is in overlapping contact with the part I I, and the part I4 is in overlapping contact with the Part II and pe ent connections may be made between these overlapping contacting surfaces by brazing them together. However, before these permanent connections are made there is considerable freedom of movement so that the terminals 6 and 1 can be very accurately and'easily prealigned even though there are substantial manufacturing tolerances or variations in the ends of coils. It will also be observed that the coils are fastened together at their outside surfaces, and not in between them so that it is relatively easy to make the brazing operation or its equivalent. In performing the brazing operation the ends or parts to be joined are bent outwardly as indicated by the dotted showing at the top of Fig. 4. The parts can then readily be clamped between electrodes (not shown) which provide the heating current.

The winding shown in Fig. 4 will readily be seen to have mechanical symmetry. It also has electrical symmetry between the terminals 6 and I, the outer conductors ll of the coil 4 which make one-half an electrical turn with respect to the core are in series with the inner conductors I 2 of the coiiB which make one and one-half electrical turns with respect to the core so that the total of these turns of this series connection is two turns. Likewise between the two terminals 6 and I the inner conductors I2 of the coil 4, which make one and one-half electrical turns with respect to the core, are in series with the outer conductors ll of the coil 5, which make one-half an electrical turn with respect to the core, so that again this part of the winding has two electrical turns. Therefore, in a sense, the winding between its terminals 5 and I consists of two parallel paths, each having two electrical turns, one being made of one-half turn plus one and one-half turns and the other being made of one and one-half turns plus one-half turn.

In the modification shown in Figs. 5' and 6 the winding has three electrical turns. This winding is also made up of duplicate coils I1, which are shown, by way of example, as also having four conductors or strands. These conductors are attached to terminals 6 and I, as in the previous figures, but they make one and one-half mechanical turns together up to the point l8 where they divide one part or pair I9 extending tangentially away from the coil and its main terminal and the other part or pair 20 extending on for substantially another one-half mechanical turn and ending along the surface 2i on the opposite side of the coil. As in the two turn coil shown in Figs. 1 through 4 inclusive, insulation 22 is inserted between the adjacent turns of the winding but it is unnecessary to have an insulating piece corresponding to the piece IS in Figs. 3 and 4 between the coils I! because the parts l9 and 2| are all at the same potential. Fig. 5 shows how the two coils I! are interfitted to form a two coil winding. -The surfaces l9 and 2| are of course permanently interconnected in any suitable manner after the coils have been properly-spaced and aligned. In Figs. 5 and 6,

the two coils each have one and one-half elec-' trical turns so that the total electrical turns of the winding is three.

While there have been shown and described particular embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therefore, it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric coil having three terminals one of which is a common terminal with respect to two effectively parallel paths between it and the remaining pair of terminals, said pair of terminals having substantially mechanically parallel surfaces, one of said pair of terminals being a projection extending generally tangentially away from a side of said coil, the other of said terminals being on the outer surface of the said coil on the diametrically opposite side thereof. 7

2. An electric coil having three terminals one of which is a common'terminal with respect to two effectively parallel paths between it and the remaining pair of terminals, said paths having an unequal number of electrical turns, said pair of terminals having substantially mechanically parallel surfaces, one of said pair of terminals being a projection extending generally tangentially away from a side of said coil, the other of aa'saadv 3. An electric coil having three terminalsone' of which is a common terminal with respect to two effectively parallel paths between it and the remaining pair of terminals, said paths having an equal number of electrical turns, said pair of terminals having substantially mechanically parallel surfaces, one of said pair of terminals being a projection extending generally tangentially away from a side of said coil, the other of said terminals being on the surface of the said 4 coil on the opposite side thereof.

4. An electric coil having three terminals one of which is a common terminal with respect to 'two effectively parallel paths between it and the remaining pair of terminals, each of said paths having the same odd number of one-half electrical turns, said pair of terminals having substantially mechanically parallel surfaces, one of said pair of terminals being a projection extending generally tangentially away from a side of said coil, the other of said terminals being on the surface of said coil on the opposite side thereof.

5. An electric coil having three terminals one of which is a common terminal with respect to two effectively parallel paths between it and the remaining pair of terminals, each of said paths having one and one-half electrical turn-s, said pair of terminals having substantially mechanically parallel surfaces, one of said pair of terminals being. a projection extending generally tangentially away from a side of said coil, the other of said terminals being on the surface of said coil on the opposite side thereof.

6. An electric coil having three terminals one of which is a common terminal with respect to two effectively parallel paths between it and the remaining pair of terminals, one of said paths having one electrical turn more than the other one, said pair of terminals having substantially mechanically parallel surfaces, one of said pair of terminals being a projection extending generally tangentially away from a side of said coil, the other of said terminals being on the surface of said coil on the opposite side thereof.

7.. An electric coil having three terminals one of which is a common terminal with respect to two effectively parallel paths between itand the remaining pair of terminals, one of said paths having one and. one-half electrical turns and the other one having one-half an electrical turn, said pair of terminals having substantially mechanicaliy parallel surfaces, one of said pair of terminals being a projection extending generally tangentially away from a side of said coil, the other of said terminals being on the surface oi! said coil on the opposite side thereof.

8. An electric winding comprising a pair of the coils, defined in claim 3, said coils being arranged with the surfaces of the respective pairs of terminals parallel with each other, each tangentially extending. terminal being in overlapping electrical contact with the surface, terminal of the other coil whereby said coils are serially connected and said winding has both mechanical and electrical symmetry.

9. An electrical coilof flatwise bent strap conductor one of whose ends has a terminal and the. other of whose ends is split into two parts of different lengths, one part having an end which projects generally tangentially of said coil away first part tangentially projects away from said coil.

10. An electric winding,'-comprising-a pair of coils definedxinclaim 9, said'coils' being laterally side by side with their terminal ends forming 0pposite mechanical and-electricalv ends of the winding, the tangentially iprojectingpart of each coil being electrically connected to the other part of the other'coil whereby. said coils-are connected in series and said winding has mechanical and electrical symmetry.

11. A winding comprising serially connecting coils, each' coll having a terminal end and an end for a connection tothe other coil, said last mentioned ends being-split into two parts one of which makes substantially one-half a mechanical turnmore than the other, the part making the, fewer mechanical turns having a generally tangentially extending projection, each projecting part being electrically connected to the part of the other coil which makes the greater number of mechanical turns.

12. A winding comprising duplicate serially connected coils for respectively linking two winding legs of a magnetic core, each coil having a terminal end and an end for connection to the other coil, said last-mentioned ends being split into two parts one of .which makes substantially one-half a mechanical turn more than the other, the part making the fewer mechanical turns having a generally tangentially extending projection,

connected coils-of radially superposed ilatwise bent conductors for respectively" linking two winding legs'of a magnetic core, each coil having a terminal end and an *end for'connection to the other coil, said last-mentioned ends being split into two parts one of whichcmakes substantially one-half mechanical turn more than the other, the part making the. fewer mechanical turns having a generally tangentially extending projection, each projecting part. being electrically connected to: the other part. onthe other coil which makes-the greater number'ofrmechanical turns whereby said winding is electrically and mechanically symmetrical- 14. A winding as in claim 12 in which each coil has the same odd number of half electrical turns.

15. 'A windinglas in claim 12 in which each coil has one and one-half electrical turns.

16., A winding comprising serially connected coils, each coilhaving a terminal end: and an end for connection to the other coil, said last-mentio'ned. ends-being splitinto two parts one of which makes substantially one-half of a mechanical turn'more than theuother, the part making the greater number ofmechanical turns having a generally tangentially extending projection, each projecting part being electrically connected to the part on the other coil which makes the fewer number of mechanical turns.

17. A substantially rectangular cross section coil fora duplicate coil wound primary winding for a current transformer comprising,v in combination, a terminal piece, at least two radially superposed strap conductors electrically connected at one end to said terminal piece,the inner of said strap" conductors-makingone' and onehalf mechanical turns and extending tangentially away from said coil at its other end. the outer of REFERENCES CITED said strap conductors making one mechanical e following references are of record in the turn and having its other end at the surface of fi f hi P en said coil. n

18. A substantially rectangular cross section STATES PATENTS coil for a duplicate coil wound primary winding m Date for a current transformer comprising, in com- 1,212,755 Fondlller Jan. 16, 1917 bination a terminal piece, at least two radially 15,13 Milton Jan. 18, 1927 superposed strap conductors electrically con-.10 ,835 Kongsted et al Oct. 24, 1944 nected at one end to said terminal piece, the inner 2, 74, 18 Johnson Apr. 17, 1945 of said strap conductors making two mechanical 2,408,211 Hodnette Sept. 24, 1 turns and having its end at the surface of said coil, theouter of said strap conductors making FOREIGN PATENTS one and one-half mechanical turns and extending 1; Number Country Date tangentially away from said coil at its other end." 393,329 France t, 22, 19

FRANKLIN R. D'ENT'REMONT. 

